The Big Bang Theory

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What is the Big Bang Theory?

• The most popular theory about the origin and evolution of our Universe

• Like all scientific theories, depending on the outcome of observations, it may need to be changed

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The Big Bang:• Occurred 12 to 14 billion years ago• The universe we can see today was only a few

millimeters across• Has since expanded from this hot dense state

into the vast and much cooler cosmos • The universe contains all of the galaxies,

including the Milky Way galaxy, where we live

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Support for the Big Bang Model

The Big Bang Model is supported by a number of important observations:

1. The expansion of the universe

2. The abundance of the light elements H, He, Li

3. The cosmic microwave background radiation

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Expansion of the Universe

In 1929, Edwin Hubble announced that his observations of galaxies showed that they were all moving away from us with a speed that was proportional to their distance from us. The more distant the galaxy, the faster it was moving away from us

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Abundance of the light elements H, He, Li

• One second after the Big Bang, the temperature of the universe was roughly 10 billion degrees

• During the first three minutes of the universe, most of the Hydrogen combined to make Helium. Trace amounts of Lithium were also produced at this time.

• We know that the amount of hydrogen, helium and lithium stays the same no matter where we look in the universe

Helium

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Cosmic Microwave Background Radiation

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Cosmic Microwave Background Radiation

• The cosmic microwave background (CMB) radiation is the radiant heat left over from the Big Bang

• The existence of the CMBs was first predicted by Ralph Alpher, Robert Herman, and George Gamow in 1948. It was first observed in 1965 by Arno Penzias and Robert Wilson

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Galaxies• Galaxies and stars formed within a few billion

years after the Big Bang• A galaxy is any large collection of stars that can

be recognized as a distinct physical entity• A galaxy has between ten million (dwarf

galaxies) to 100 trillion stars• There are more than 100 billion galaxies in the

universe

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The Milky Way Galaxy •Our home galaxy

•About 100,000 light years across

•2 Main Spiral Arms

•It has over 200 billion stars

•There is a black hole at the center

•It's part of the Virgo Supercluster, a grouping of galaxies within 150 million light years

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You Are Here

The Milky Way Galaxy

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Astronomical Address

• Sam and Sally Student• 112 Elm Street• Byfield• Massachusetts• USA• Earth (Third planet from the sun)• The Solar System• Milky Way Galaxy• Virgo Supercluster• The Universe

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• Expansion of Universe• http://www.youtube.com/watch?v=iCI8K9mD

_yU• Birth of our solar system• http://www.youtube.com/watch?v=B1AXbpYn

dGc&feature=fvw• Hadron collider• http://www.youtube.com/watch?v=jlY4OBNo

1T8&feature=related